Change speed mechanism



ug. 24, 1937. P. MATTIA CHANGE SPEE MECHANISM Original Filed March 7,1934 2 Sheets- Sheet 1 l. i QS FWHM Aug. 24, 1937.

P. MATTIA CHANGE lSPEED MECHANISM original Filed March 7, 1934 2Shee'cs-SheelI 2 Patnied Aug. 24, 1937 UNITED STATES PATENT OFFICEApplication March 7,v 1934, Serial No. 714,484 Renewed February 25,1937. In Italy July 29,

2 Claims. '(Cl. 74-260) The invention concerns one of those gears ormechanisms which are known as change speed gears as are generally usedwith motor cars, but which may be used for power transmission ingenerali One object of the invention is to improve the known epicyclicgear train.

A further object of the invention is to provide a mechanism adapted tochange the speed ratio automatically changed over a driven shaft, when adetermined change of the load takes place.

A further object of the invention is to clutch the driven shaftautomatically to the power shaft as soon as thc latter reaches a certainload or l5 speed.

Another object of the invention is to connect in serial a plurality ofimproved epicyclic gear trains to obtain a variety of torques over thedriven shaft.

Another object of the invention is to provide means whereby thecentrifugal force developed in a drum subjected to a planetary rotation,may be utilizedI to counteract the rotation of said drum on its ownaxis.

A further object of the invention is to provide an epicyclic gear trainhaving a, spur wheel capable of rotating in one direction only to theleffect of allowing a loose rotation of the train in said same directionwhen the driving shaft is directly clutched to the driven shaft.

With these and other objects in view, the invention will now bedescribed with reference to the annexed drawings in whichz-` Fig. 1 is asectional view of a mechanism designed according to the invention.

- Fig. 2 is a section on line 2-2 of Fig. 1.

Fig. 3 is a cross-section of a drum connected to the mechanism.

Fig. 4 is the cross-section of a second form of construction of saiddrum'.

Fig. 5 is a side view of a free-wheel mechanism embodied in theinvention.

As shown in Fig. 1, two identical mechanisms are illustrated, mountedone after the other.

With two mechanisms three different torque To each axle 3 is fastened aspur wheel 4, a

spur wheel 5 and a drum 6. The wheel 5 meshes with a free wheel IIcoaxial to the power shaft 55 and which, through a one way brakemechanism (Fig. 5) I3, I4 has a connection to a dependent part p of thestationary housing of the gear in order to allow said one way brake torotate freely in the driving direction of the power shaft while beingprevented to rotate in the opposite 5 direction.

A secondary shaft 9 mounted in alignment with the power shaft I isrotatably connected theretoby means of the hub of the wheel 8, I0, bothshafts I and 9 bearing as a unit on the walls p 10 of the housing.

The spur wheel 4 meshes with a spur wheel 8 fastened to the secondaryshaft 9. The drum 6 (Figs. 3, 4) has an annular cavity l (2l in Fig. 4)whichmay be discontinued totally at a certain 15 point by means of awall I8 (Fig. 3) or may be partially discontinued at various points(Fig. 4) by means of radial vanes a which project from the periphery ofthe cavity 2l with a certain inclination in respect of the radius of thedrum. In the latter described form of construction of the drum, thecavity 2l is.. continuous in the vicinity of the hub.

In the said drum, hermetically closed, there is lodged a. certain'amount of a high density fluid, 25 preferably mercury, to the effecthereafter described.

I have described one mechanism, but in the drawings a further one isillustrated which is connected to the secondary shaft 9 in the same 30way as the rst mechanism is connected to-'the power shaft I. Thereforethe second mechanism needs no further description, it being implicitthat the further wheels 4, 5, II, 8 have the already mentionedinterconnections and that, in 35 this second mechanism, the shaft 9 maybe considered as a power shaft, there being a driven shaft I9 mounted inalignment thereto.

The compound gear acts as fo1loWs:-.

If We imagine the described gear applied to a 0 motor car it may beconsidered that at the start of the car, a considerable resistance isoffered to the movement, therefore a considerable torque will benecessary to the driven shaft I9 to set the car in motion. 45

It is therefore desirable that the speed may be transmitted from thepower shaft I to the driven shaft I9 through a low speed ratio.

By starting the engine, the power shaft carries in rotation the doubledisc carriers 2. Said cark riers carry in revolution about their ownaxis, the wheels 4 and 5 (planetary wheels) and the drum 6. 1 Saidwheels 4 and 5 by meshing with the wheels 8 and II get their reaction.The reaction of 55` wheel 8 is derived from the resistance of themachine (load), the reaction of wheel il deriving from its impossibilityto revolve in one direction. Both reactions combined have the dynamiceffect of driving the axles 3 with the wheels 4 and 5 pinned thereto,while the wheels d drive the wheel 8 pinned to the secondary shaft 9.

We have thus a transmission of power from shaft l to shaft 9 at acertain rate of speed (differential speed) and with correspondentincrease of the torque, which may be calculated according to knownfunction given by any manual of kinematics in connection with the socalled epicyclic gear train.

The secondary shaft 9 on its turn carries in rotation its own doubledisc carrier 2 which carries in revolution the second set of axles 3with the respective wheels d and 5 and the drum 6, said wheels 4 and 5meshing respectively with correspondingwheels 8 and Il which react inthe already described manner, to set in rotary motion the wheels 4 and 5and to drive the further shaft i9 through Wheel 8 of said secondmechanism, at a rate of speed further reduced.

With such reduced speed there is of course a corresponding increase ofthe torque acting on' shaft 9 which causes the motion of the car.

The car being in motion it does not need the high torque employed tostart. The lower load causes an increase in the speed of the engine,while of courseythe shaft I revolves at higher speed than the shaft 9.The speed of the shaft i which carries in rotation with the double discmember 2 the drum 6, may be high enough to develop a considerable amountof centrifugal force in the mercury contained in the cavity of the drum6. Said force, bearing on the wall l or on one of the vanes acounteracts the rotation of the drum on its own axle 3 and balances theresistance offered by Wheel 8. In such conditions the rotation of thewheels 4l and 5 is blocked with the rotation of the axles 3 and we havea rigid clutch of said Wheels with the Wheels H and 8.

The Wheel 8 is thus driven in direct connection with the power shaft i.In said direct driving, the wheel Il being driven in the sense of itsfreedom, revolves loosely on its own axis.

If the car encounters a resistance (up hill, brakeage) we return to theinitial conditions of high load, the drum 6 decreases its speed, thedirect clutch disappears with the decrease of the centrifugal force, andboth mechanisms retake their function of decreasing the rate of speed atthe driven shaft, and increasing the torque correspondingly. A directcoupling of the three shafts i, 9, i9, is obtained when by suitablecarburation, the shafts l and 9 run with high enough speed in relationto the load.

Having now fully described the nature of my invention and the manner inwhich the same should be performed I declare that what I claim 1. In achange speed mechanism comprising a driving shaft and a driven shaft, acarrier fastened to said driving shaft and a toothed Wheel keyed to saiddriven shaft, couples of planet wheels of different diameters keyed onaxes symmetrically arranged on said carrier and parallel to said shafts,the smaller of said wheels meshing with the toothed wheel on said drivenshaft, said mechanism being contained in a stationary housing, a centralspur wheel mounted on said. housing concentric with said shafts andprovided with a one-way brake made of ratchet and rollers to allowrotation of said spur wheel in the rotating direction of the drivingshaft only, said spur wheel meshing with the larger planet wheels; adrum keyed on the axis of each planet couple, said drum having anannular cavity partially discontinued at various points by means ofradial vanes which project from the periphery of said cavity with acertain inclination in respect of the radius of the drum, said cavitycontaining mercury.

2. A mechanism of the character described comprising, in combination, adriving shaft and a driven shaft, a carrier fastened to said drivingshaft and a toothed wheel secured to said driven shaft, couples ofplanet wheels of different diameter rigidly operatively connectedtogether and mounted on said carrier and arranged on axes parallel tosaid shafts, the smaller of said wheels meshing with the toothed wheelon said driven shaft, said mechanism being contained in a stationaryhousing, a central spur wheel mounted on said housing concentric withsaid shafts and provided with a one-way brake to allow rotation of saidspur wheel in only the direction of rotation of the driving shaft, saidspur wheel meshing with the larger planet wheels, and a drum rigidlyoperatively connected With each planet couple, said drum having anannular cavity partially discontinued at various points by means ofvanes projecting from the periphery of said cavity at an angle withrespect to the radii of the drum, said cavity containing a heavy fluid.

' PIETRO MATTIA.

